1. Field of the Invention
The present invention relates to a solid-state image sensing device and, more particularly, to a CMOS image sensor used in a cell phone, digital camera, or video camera equipped with an image sensor.
2. Description of the Related Art
A conventional method of widening the dynamic range of a CMOS image sensor is described in, e.g., Jpn. Pat. Appln. KOKAI Publication Nos. 2001-189893 and 2000-23044. In Jpn. Pat. Appln. KOKAI Publication No. 2001-189893, the method of widening the dynamic range is applied to an incomplete transfer type photodiode. However, with this method an afterimage or white spot may form, and it is difficult to improve the image quality. To the contrary, the method in Jpn. Pat. Appln. KOKAI Publication No. 2000-23044 is applied to a complete transfer type photodiode. However, the dynamic range is widened using a detector, so nonuniformity in the dark and KTC noise may arise from leakage from the detector. The image quality may be degraded by a factor different from that in Jpn. Pat. Appln. KOKAI Publication No. 2001-189893. According to either method, a signal obtained by adding signals corresponding to long and short exposure times is output. It is difficult to divide the signal into those corresponding to long and short exposure times.